Krobylos laosensis ( Saurin, 1953 )

Inkhavilay, Khamla, Sutcharit, & Chirasak, 2024, A new pulmonate microsnail species in the genus Boysidia, with remarks on Bensonella and Krobylos species (Pupilloidea: Hypselostomatidae) from northern Laos, Raffles Bulletin of Zoology 72, pp. 438-449 : 446

Krobylos laosensis ( Saurin, 1953)

( Fig. 5 )

Pyramidula laosensis Saurin, 1953: 119 , pl. 4, fig. 11a–c. Type locality: environs du village méo de Pah Hia, à 100 kilomètres au Sud de Xieng-Khouang , chef-lieu de la province du Tran Ninh, Laos [probably refers to Ban Namthong, Longchaeng District , Xaisomboun Province, Laos] .

Krobylos laosensis — Páll-Gergely et al., 2015: 31 (abstract), 55. Inkhavilay et al., 2019: 60 , 61, fig. 26e.

Material examined. Holotype MNHN-IM-2000-31746 ( Fig. 5A ) from Pah Hia. CUMZ 14425 (9 shells; Fig. 5B, C ) from Tham Piew Cave , Muang Kham District, Xiangkhouang Province, Laos (19°40′24.8″N, 103°34′05.7″E) coll. K. Inkhavilay and C. Sutcharit, August 2015.

Description. Shell small, conical, slightly higher than width, reddish brown, 5–5½ convex whorls. Apex round; protoconch about 1–1½ whorl with weak wrinkles and spiral ridgelets. Teleoconch with strong, irregular growth lines, and sometimes growth lines conspicuously white. Suture impressed, deep. Last whorl large, rounded to weak angular (stronger on earlier whorls). Aperture wide, rounded, without any dentition, reddish brown inside. Peristome pale yellowish, little thickened, weakly expanded. Columellar whitish, straight, dilated, overhanging umbilicus. Umbilicus narrowly perforate, about one-fifth of shell width, rounded, deep.

Distribution. This species was previously known only from the type locality ( Saurin, 1953; Páll-Gergely et al., 2015; Inkhavilay et al., 2019), and a recent record is from Xiangkhouang Province.

Remarks. Although the syntype is small (width about 2 mm), with around four whorls, and a simple and sharp peristomal lip, it probably represents an early or immature shell stage. We considered our newly collected specimens to be this species, although with slightly weaker angular whorl (on spire) and irregular shell surface. In addition, the new collection locality in Xiangkhouang Province is geographically proximal, roughly 90 km northeast of the type locality, ‘Pahai’ [roughly in present-day Xaisomboun Province].

This species is very similar to K. clerxi Maassen, 2008 from Luang Namtha Province, about 350 km northwest of the type locality, in most shell characters. However, K. laosensis has a slightly ascending last whorl near the peristome, while K. clerxi has a slightly descending last whorl near the peristome ( Maassen, 2008; Páll-Gergely et al., 2015; Inkhavilay et al., 2019). Nevertheless, we regard the two species as distinct until more detailed studies to clarify their systematic relationships become available.

Figures

Fig. 5. Krobylos laosensis (Saurin, 1953). A, syntype MNHN-IM-2000-31746 from Pah Hia. B, C, specimen CUMZ 14425 from Muang Kham, Xiangkhouang, Laos. B, shell and C, protoconch. Photo: B. Páll-Gergely (A).